1. Field of the Invention
This invention relates to polyoxyalkylenes made by polymerizing at least one alkylene oxide in the presence of an initiator and a basic catalyst.
2. Description of the Prior Art
Login in U.S. Pat. No. 4,118,326 discloses that a polyoxyalkylene can be neutralized with a saturated carboxylic acid containing up to 18 carbon atoms subsequent to polymerization of alkylene oxides with an active hydrogen-containing initiator in the presence of an alkaline catalyst such as potassium hydroxide. Instead of removing the alkaline catalyst residue remaining subsequent to polymerization of the polyoxyalkylene, formation of the salt with the above saturated carboxylic acid provides improved oxidation stability when the polyoxyalkylene is utilized as a spinfinish lubricant for processing synthetic fibers.
Newkirk et al in U.S. Pat. No. 4,110,227 discloses lubricants for synthetic fibers such as polyester and nylon which are oxidation-stable polyoxyalkylene compounds. The polyoxyalkylenes are initiated utilizing a difunctional phenol as an active hydrogen-containing compound. The presence of the phenolic initiator compound residue in the chain of the polyoxyalkylene provides improved heat stable polyoxyalkylene lubricants.
Brenkman et al in U.S. Pat. No. 3,365,402 disclose a process for eliminating the harmful effects of an alkaline catalyst in a capillary-active product (polyoxyalkylene). Catalyst ions remaining after the polymerization of the polyoxyalkylene are neutralized with a laurylpolyoxyethylene acetic acid. Such a product is chosen so as to provide compatibility with the polyoxyalkylene main product and so as not to impair the properties of the main product.
Mago in U.S. Pat. No. 4,263,167 discloses that an effective amount of the sodium salt of salicylic acid is a good oxidation inhibitor for poly(alkylene oxide) present at 10 percent aqueous concentration when exposed to a temperature of 70.degree. C. for 8 days but was not a good corrosion inhibitor for steel. Methylene or sulfur-bridged hydroxyl-substituted aromatic carboxylic acids are both oxidation inhibitors for poly(alkylene oxides) and good corrosion inhibitors for steel.
It has been the practice generally to neutralize the residue of the alkaline catalyst utilized in the preparation of polyoxyalkylenes. Inorganic acids have been added so as to form soluble salts or precipitates which are subsequently filtered out so as to remove alkali or alkaline earth metal ions. In those cases where the inorganic acid utilized forms soluble salts with the alkaline catalyst, for instance potassium phosphate, it has been found possible to utilize the neutralized polyols in the preparation of certain types of polyurethanes. Alternatively, the prior art use of adsorbents such as magnesium silicate in the presence of water followed by filtration provides a means of removal of the metal ions derived from the alkaline catalyst. It remains to this date industry practice to remove the metal ion residue of the alkaline catalyst from a polyoxyalkylene intended for use in the preparation of polyurethanes. No more than about 5 ppm of alkali or alkaline earth metal ion is allowed in said polyoxyalkylenes.
Common approaches to the removal of the alkaline catalyst have been adsorption on magnesium silicate or the neutralization of the alkaline catalyst with an inorganic acid which forms a precipitate and the subsequent removal of the precipitate or the magnesium silicate by filtration. Various other means of removal of the alkaline catalyst have been proposed such as dilution of the polyoxyalkylene with a water insoluble solvent and the subsequent washing of the solvent solution with water. Another approach has been the use of ion exchange columns for the removal of catalyst from low viscosity polyoxyalkylenes. A further approach is the neutralization of the alkaline catalyst with carbon dioxide, and the subsequent removal of water under reduced pressure with the subsequent removal of the alkali carbonate formed by filtration.